Method of making milling cutters



F. MULLER. 7 METHOD OF MAKING MILLING CUTTERS. APPLICATION nuso juLvzs'. wan-RENEWED JULY 19. 1922.

1,429,616., I PatentedSeptfiIQ, 1-922;

. Patented Sept. 19, 312 922.

UNHTED amt oarica.

rarnnnmcn MULLER, or HARTFORD, CONNECTICUT, 'assrclvoa TO m 'awm'r- HEY comranr, or NEW YORK, arr, A CORPORATIQN or-Nnw JERSEY.

iim'rnon or MAKING rantm'iiaev Carri-ms.

. ori inal application filed March a1, 1919, Serial No. 286,524. Divided and this application filed July 29, 3 1 1920, Serial No. 399,717. Benewed To all whom it may 001L067f7l." J

Be it known that I, FnmnERI-C-H 'Mr'iLLER," a citizen of the United States, residing at Hartforch'in the county of Hartford and State of Connecticut, have invented certain new. and useful Improvements in Methods of Making Milling Cutters,'of which the following isa specification.

In practising the method involving the invention use is preferably made of a machine which is in some respects similar to that shown in my copending application for metal cutting machines, Serial No. 286,524,

' n filed March 31, 19195 This present application. is a di'vision of the said application. The specific. machine herein illustrated 18 set forth and; claimed in my copending applicationfor metal cutting machines, Serial No. 399,716, filed on even dateherewith.

A -machine of 'the type disclosed in the said applications is preferably relieve a milling cutter or other similar'object, and, considered more specifically, a machine of this type is adapted to accurately relieve a cutter blank and provide it .with a contour which conforms exactly to former which is inserted in the'machine.

Under most circumstances .the former which is provided exactly the same as the contour of the milling cutter. Occasionally, however, it is preferable or more convenient to provide a former having a contour which is the reverse of the contour desired on the milling cutter.

For instance, itmay be desirable to utilize as a former a sample of the work which the millingcutter is intended to cut. (hen a former of reverse shape is provided it is necessary to utilize a machine which is somewhat different from the preferred form of machine as shown and described in the said application.

The principal object of the present invention, therefore, is to provide a method by means of which a milling cutter can be relieved and shaped in accordance with a cutter having a contour of reverse shape. 1 further object of the invention is to proyide a method which includes a step-by-step feed of the former pin and cutting; tool, the grooves in the cutter blank being utilized to permit the movement of the tool inward (instead of outward) at the time of each longitudinal feeding movement. -Other ob- .]ects of the invention will be apparent from adapted to .form and.

the contour of a predetermined r vided, as shown at 4. Preferably the'headhas a contour which is July 19, 1922. Serial No. 576,149.

the following specification and claims.

In the accompanying-drawings I have shown the essential features of a machine adapted for use in practising the invention. Many of the details, however, have been omltted as these are or may be the same as tion Serial No.1286,524 and are not necessary fora full'funderstanding of the method.

0f the drawings: Figure lwis a fragmentary combined elevational and sectional view of the machine.

' parts of the machine are mounted. For carrying the blank for .the tool to be'formed and relieved, there is provided a headstock Qandt preferably also a tailstock 3. A tool holding-endoperating mechanism is proshown in my aforesaid copending applica- I as to hold the blank against longitudinal movement, the tool mechanism 4 being moved longitudinally along the blank in the manner to be presently set forth. When the machine is so constructed, the'headstock 2 is fixedly secured to the bed, preferably being formed in part integrally therewith, as shown. The tailstock 3 is adjustable along the bed to accommodate blanks or blank arbors of different lengths.

The headstock 2 is provided with a rotatable spindle 5 mounted in bearings 6 and 7. Secured to the spindle is a collet chuck 8 which may be of any usual or preferred form and which is adapted to grip either the shank of the tool to be formed and relieved or an arbor upon which the tool is mounted.

-As illustrated in Fig. 2, there is av blank A mounted upon an armor B, the arbor be ing engaged by the shtick-,8. For rotating 'the cutting too-l 25. The

which is the adapted .to receive T-bolts through the former.

ways 22 and 23 on the bed 1. Mounted for transverse movement with respect to the carriage'2l is a slide 24,

tool 25 is prefer ably ver narrow, but if desired a wider tool can e used-in certain conditions.

A former and former pin, are provided for controllin -or guiding the tool so as to cause 1t to cut the blank with a predetermined contour. As illustrated, there is provided a former 26 carried by the bed, this former having a shape reverse of the shape desired to be cut on the blank A; 25 engages the blank at the front thereof, and, this being the case, the former 26 1s so arranged that the efi'ective'side thereof faces rearward, this rearward side being engaged by aformer pin 27 The former pin is secured to the slide 24 by means of a bracket 222. When the cutting .tool 25 is symmetrical, as shown, the former pin 27 is also symmetrical. and has the same size and shape as the tool. The former pin is detachably secured to the slide so that it can be removed and another pin substituted corresponding to a tool differing'in size or shape from the tool 25 which is shown.

For supporting. the former 26 there is provided a bracket 28 rigidly secured to the bed 1. In order-to permit adjustment, the former 26 is secured to a slide 29 which is longitudinally movable along a suitable guideway 30 on the bracket, a screw-31 being provided for effecting longitudinal movement. The slide can be locked in adjusted position by means of screws 82, 32 engaging a gib 33. As illustrated, the former 26 is secured to a plate 26 and in order to permit the ready attachment of the former,

the slide 29 is provided with a T-slot 34 85 passing -To further assist in holding the former in place and to prevent any possible free movementthereof, there is provided a hooked bolt 36 which, when tightened, serves to draw the plate 26 back The machine may be and preferable is provided with means for effecting relieving movements of the tool. lt'is to be understood that the invention is applicable either to a machine having suitable relieving mech anism or to one without such mechanism. The novel features of the machine embodying the invention have a peculiar cooperative relationship with the relieving mechanism when that is provided.

As illustrated, the tool is not rigidly secured to the slide 24 but is transversely movable thereon. Mounted on the slide 24 is a slide 37 which is transversely movable along a suitable guideway. Carried in part by the slide 24 is a mechanism for effecting regular reciprocating relieving movements this slide carrying and outward to follow the The cutting tool so'as to withdraw the aaaafere of the slide 37 and the tool in suitable timed relation with the rotative movement of the blank. In order that the tool may be adjusted for blanks of diflerent sizes, there is provided a tool-carrying slide 38 transverse ly adjustable on the slide 37. It will be observed that with the construction described the toolis maintained in parallelism as it moves longitudinally for feeding or inward contour.

The relieving mechanism for moving the slide 37 together with the tool a rotatable relieving cam 46 which is mounted on the slide 24 so as to be bodily movable therewith. As shown, the cam is mounted on a longitudinal} rotatable shaft 47 mounted inbearings 48 and 49 on a bracket '50 depending at the front of the slide 24*. A lever 51 is pivotedbetween its ends-on the slide24' and at its lower end is provided with a roller engaging the cam 46. The .upper end of on the slide 25 includes the lever engages an abutment 52 37. A-coil spring 53 is interposed between the slide 37 and the'slide v The shape of the cam 46is such that the s1ide37 is moved forward relatively slowly at a uniformrate' so that the tool. may effect a and is then drawn back relatively rapidly another out.

As before stated, the cam 46 isdriveri iu timed relation with the blank rotation. rotating the cam, ,I make use of the aforesaid transverse shaft 11. Positioned imme diately below the shaft 11 is a shaft, 54 which is mounted partly in the main frame and partly in a bracket 55 secured thereto. F or connecting the 'two shafts 11 and 54 there is provided a a gear 57 on the shaft, 54 and an idler gear 58 meshing with the two gears 56 and 57. The idler *gear ismounted on a bearing stud 59 carried by an adjustable slotted arm 60. The speed ratio between. the two shafts 11 and 54 can be changed by removingone or both of the gears other gears of different diameters, it being clear that the idler gear 58 can be adjusted to mesh with such difierently diametered gears. Mounted in the said bracket 55 is a vertical shaft and this shaft is driv'en the shaft 54. by means of bevel gearing By means of bevel serves to.drive a longitudinal splined shaft 65. This shaft is supported partly in a bearing 66 secured to the bed and partly in bearings 67 in a depending bracket 68 secured to the carriage 21.

relieving "cut,

tool and position it for gear 56 on the shaft 1-1,

56 and 57 and substituting tee - ed in the bracket the slide 24.

supported by the is transmitted "to the bracket 68.

Mounted on the shaft 65 between the bearings 67 and splined to the shaft, is a-worm 69. 70 which is connected with a transverse shaft71. The worm 'Wheel and the shaft are rotatably mounted in a bearing 72 form-. 68, and in a bearing 73 formed on a supplemental bracket 74 secured Slidably mounted on the shaft 71 is a bevel gear 75, and this gear is engaged by a bearing 7 6 on the aforesaid bracket 50 depending from the front end of The bevel gear- 75 meshes with a bevel gear 77 on the shaft 4:7. The bevel gear 77 and the shaft 71 are splined or otherwise suitably constructed so that the bevel gearisrotated, but is at the same time free to move transversely"of the machinewhen the slide '24 is moved.

Inasmuch as the bevel gears 75 and'77 are both bracket 50, they are at all times held in mesh.- It will be seen that with this construction po'wer'is transmitted from the shaft 11, through the several parts that have been described, to the shaft 65, and from the shaft 65 to the shaft &7- and the-cam 46, the connection between the shaft 65 and the shaft 47 being suchthat free transverse movement of the cam and associated parts is permitted. The cam 46 is given one complete rotation for each tooth of the blank.

' In order that blanks with helical teeth may be properly formed and relieved, it is necessary to effect the relieving movements of the tool in peculiar relation to the rotative movement ofthe blank so that the relief may be in conformity with the helical teeth. I have stated that the relieving movements of the tool are effected in timed relation to the rotative movement of the blank; and, for any given position f the carriage, this timed relation is fixed and definite, but when the carriage is moved tobring the tool into a new cutting position, it is necessary to vary the relation between the relievingmovements of the tool and the rotative movement of the blank.

In the construction illustrated, the worm 9 is not connected directly with the spindle suitable gearing which can be supplementally moved to change the spindle rotation. By preference, this gearing is bodily rotatable and includes a rack and pinion, the rack being longitudinally slidable in accordance with the longitudinal movements of the carriage 21. Coaxially mounted with the spindle 5 is a sleeve 79, this being supported in bearings 80 and 81 in the headstock. ablv extends into and has a bearing in the outer end of the spindle. The aforesaid worm 9 is rigidly secured to the sleeve 79. Associated with the spindle is a frame 82 This worm meshes with aworm Wheel .is moved longitudinallv the fork 103 with The inner end of the sleeve preferthe carriage and which is recessed to receive the outerend I of the spindle and engage ,the outersurface thereof. Slidably mounted sleeve 79 is a shaft 83 having rack teeth formed thereon at 84, The shaft 83 is splined to the sleeve 7 9 so as to be rotatable therewith. Rotatably mounted in bearings inthe frame 82 is a transverse shaft 85 pro vided with teeth v86 which meshes with the rack teeth 84. Also rotatably mounted in the frame 82 is a transverse shaft 87 The two shafts 85 and 87 are connected by spur gears 88 and 89. Also rotatably mounted in the frame 82 is a third rotatable shaft 90, to which is secured a worm 91. This worm meshes with worm teeth 92 formed in the periphery of the spindle 5 near the end there of. At the side of the bracket 82 opposite from the gears 88 and 89 there is provided gearing- (not shown) for connecting the shafts 87 and 90.

Carried by the shaft 83 at the outer end thereof is an annularly grooved collar 100. Rigidly secured to the main frame adjacent the shaft 83 is a longitudinal guide stud 101. Slidably mounted on the stud 101 is a bracket 102 having a fork 103 entering the groove in the collar 100. The bracket 102 is apertured to receive a longitudinal rod 104 which is connected at its right-hand end with the carriage 21. The bracket 102 in the can be clamped to therod 104 in any desired relative position.

It will be seen that when the carriage 21 0 along the bed the rod 104, together with the bracket 102, will be moved at thesame time and to the same extent. By reason of the engagement of the collar the shaft 83 is similarly moved, thus moving the rack teeth 84. When the rack slides longitudinally the pinion 86 is turned and this serves, by means of the gearing and the several shafts that have been described, to turn the worm 91. The rotative movement of the form 91' serves to turn the spindle 5 relatively to the frame 82 and the sleeve 79. It will be understood, as before stated, that the entire gearing sleeve 79. It will therefore be clear that f the relative movement of the spindle with respect to the sleeve simply serves to either increase or decrease the spindle rotation to a certain extent. However. the relative move-' mentwof the spindle is determined by the longitudinal movement of the rack 8 1, wh ch in turn is determined by the longitudinal movement of the carriage 21 and of the cutting tool 25 carried thereby. Inasmuch as the relieving cam reciprocates the tool with a frequency which is normally uniform, and inasmuch as the spindle and the blank are given a changed rotation which is in exact proportion to the longitudinal movement of 78 rotates bodily with the the tool, it is clear-that the rent wing movements are efl'ected in such relation to the blank as to be in conformity with helical teeth.

F or moving the carriage longitudinally along the bed there is provided a screw 107 which engages a nut 108 carried by a bracket 109 depending from the carriage. The screw is supported at its left-hand end in a locating 110 formed in'a bracket 111 se- ,cured to the bed. Mounted in the bracket 111 is a transverse shaft 112 which is connected with the screw 107 by means of bevel gearing 113. At the front end of the shaft 112 is a hand wheel 114 by means of which the screw may be turned manually to move the carriage. In order that the carriage may be moved automatically to feed the tool from one cutting position to another, a suitable mechanism is provided. This mechanism is adapted to feed the carriage intermittently. Mounted in the bracket 111 is a transverse bearing pin 115 upon which is mounted a gear 117 which meshes with a gear 118 on the shaft 112: Connected with this gear 117 is a ratchet wheel 119. Loosely mounted on the hub of the ratchet wheel is a swinging arm 123. Pivotally connected with this arm near the lower end thereof is a link 124 which is adjustably connected at its left-hand end with an oscillating crank The crank arm is secured to a Carried by the lever at the upper end thereof is a roller positioned to be engaged by a'cam 130 on a longitudinal rotatable shaft 131. Mounted on theswinging arm 123 is a pawl 133 adapted to engage the ratchet wheel 119. The shaft 131 is rotated in the manner to be presently described, and it will be seen that at each rotation thereof the arm 128 and the crank arm 12 5 are oscillated. By means of-the link 124 the oscillation of the crank arm 125 is transmitted to the plate 123, the extent of oscillation of the plate being adjustable by changing the connection between the link I and the crank arm. By means of the pawl 133 the ratchet wheel 119 is turned through a small angle, thus turning the shaft 112 and the lead'screw 107 and moving-the carriage. i

The machine includes two alternately operable mechanisms, one for turning the spindle'and reciprocating the tool for effecting relief, and the other for feeding the tool. These mechanisms are not herein shown or described in detail. It is desirable to feed the tool longitudinally while out of engagement with the blank, that is, when the tool is opposite the groove between two teeth of the blank. Theblank is. turned through approximately one revolution and is preferably mounted in the spindle so that at the position of stopping the tool will be opposite a groove. The grooves are helical respect to the feeding movements.v

former pin.

rename ment, this supplemental turning exactly compensating for the inclination of the grooves and. insuring the stopping of the blank with a groove opposite the tool.

Preferably the former pin and the former are separated at the time of each longitudinal' movement. In accordance with 'one feature of the invention the former and former pin are separated by moving toward the rear the one of them that is rearmost, the machine in this respect being different from that specifically claimed in my aforesaid application. -When the pin is rearmost, as herein disclosed, the toolseparation is effected by moving the pin rearward, the tool preferably also being similarly moved at the same time.v This withdrawal of the former pin is effected by mechanism actuated by the shaft 131 which operates intermittently, the withdrawal being properly timed Awith ssociated with the slide 24 is an abutment 180 which is enga ed by the upper end of a lever 181 'longitud1nally pivoted to the carriage 21. The lower end of the lever is provided with a roller which is adapted to be engaged by a cam plate 182 on a cam disk 183 secured to the shaft 131. At the beginning of the rotation of the shaft-131 the cam plate 182 engages the roller on the lever 181 and swin s it in the clockwise direction, thus moving t e abutment 180 together with the slide 24* toward the rear. The longitudinal feeding movements and the rearward movem-ents of the pin and tool areso timed that the tool is always opposite a groove in the blank A when moved. This makes the rearward movement of the tool possible.

As the shaft 131 continues to rotate, the cam 130 operates the feeding mechanism in the way already described and the carriage is moved longitudinally along the bed. After that the cam plate 182 permits the lever 18]. to return. to the position shown and the slide 24 moves forward, permitting the tool 25 and the former pin 27 to return to their new operative positions. It will be seen that by thus withdrawing the former pin from theform'er at the time of longitudinal movement I avoid any difiiculties incident to forcing the former pin along the former while in contact therewith. If the former pin were maintained in contact with the formerat alltimes difficulty would be experienced in effecting the longitudinal movement, particularly at places where the contour of the former is sharply inclined. .F or steep inclines such as herein illustrated, it would be impossible to thus move the For returning the slide 24 forward to its operative position a fluid controlled mechanisin may be provided, such as fully deshown a somewhat simpler mechanism which may be suitable for many classes of movable on work. I have shown coil springs 205 which are located in transverse apertures 206 in the slide 24*. These springs abut at their rear ends against brackets 210 on the carriage 21 and abut at their front ends against plugs 223 fitted into the apertures.

'The before mentioned abutment 180 is not connected directly to the slide 24 but is connected to a second slide 184 which is transversely movable independently of the first slide 24. Springs 185 posed between the slide 184 and the carriage 21 and these springs tend to move the slide 184 forward, thus holding the abutment 180 at all times in engagement with the lever 181 The two slides 24 and 184 are ordinarily connected by a lock. As shown most clearly in Fig. 4, the lock includes a plate 186 located in a recess in the top of the slide 24. The plate is provided with a boss which projects slot in 'theslide, and threaded into this boss is a vertical stud 187. This stud extends through and closely fits an aperture in the slide 184. Pivoted to the two small bell-crank levers 188, these levers having horizontal upper arms which engage a collar on the stud 187. The lower ends of the levers are adapted to be engaged by a tapered cam bushing 189 vertically the stud. When the bushing 189 is in its lower position, as shown, the levers 188 are forced outward, thus drawing the stud 187 downward and forcing. late 186 into clamping engagement the with the slide 24. .In this way the slide 24 is firmly connected with the slide 184*. When the bushing 189 is in its raised position, the levers 188 swing inward, thus permitting the stud 187 to move upward and release the plate 186 from its clamping engagement with the slide 24. For moving the bushing 189 there is provided a forked lever 190 having projections engaging slots or notches in the bushing. This lever is secured to a longitudinal rock shaft 191 mounted in hearings in the carriage 21. Connected with the lever 190 is a lever 192 having a roller which is adapted to be engaged by cam plates 193 and 194 secured to a cam disln 195 mounted on the shaft 131. It will be seen that as the shaft 131 rotates, the cam plate 193 engages the roller on the lever 192, thus moving the lever 190 and the cam bushing 189 upward and releasing the lock. Subsequently the roller is engaged by the cam plate 194, thus moving the cam bushing 189' downward and re-engaging the lock. 7

T have already stated that a supplemental are interdownward through a.

slide 184 are as it has been released mechanism is provided for returning the slide 24 after it has been moved in the way before described. Preferably, in order that this supplemental returning mechanism may operate without being affected in any way by the return movement of the slide184,

and in order further that the slide 24 may be returned with a minimum of effort, I provide a supplemental means for supporting the slide 24 after it has been unlocke from the slide 184. riage 21 is provided nearits front and rear with transverse pivot pins 196 and 197. The carriage is slotted adjacent the pins, and in these slots are positioned arms 198 and 199 respectively pivoted on the said The arms are respectively provided pins. with rollers 200 and 201 which are adapted to engage the bottom of the slide 24.

arms are connected by pivoted links 202, and these links in turn are connected by a transverse yoke 203. .The yoke 203 is pro- As illustrated, the car- The,

vided with slots or notches in which fitpivot bosses projecting upward from the lever 190. The result is that when thelever 190 is swung upward to release thelock, the arms 198 and 199 are swung in a clockwise direction, thus swinging 201 upward so as to lift the slide 24 off from the slide 184 and support it inde pendently. Theactual raising of the slide maybe but a few thousandths of an inch. For returning the slide 24* rearward as soon by the lock and elevated by the rollers, there are provided coil springs 205 as aforesaid.

It will be noted that the several cams 130, 182, 193 and 194 are so positioned in relation to each other than the operations which they respectively control take place in the following order. First the two slides 184 and 24 are moved rearward in unison, they being still locked together. Then the slide 24 is unlocked from the slide 184 and is at the same time elevated on the rollers 200 and 201. At or about the same time the carriage is moved longitudinally to bring the former pin and the tool to new operative positions. Then the slide l84 is permitted to return forward to its normal position. In the meantime the slide 24 is being moved forward under the control of the springs 205*. After thecompletion of the said return movement. of the slide 24 the rollers 200 and 201 are lowered and the slide is again locked to the slide 184 It is believed that the method followed in the operation of the machine will be clear from the foregoing description and that a very brief summary will suffice. A former 26 is provided having a contour whichis the reverse of the desired contour and a blank is put in place, this blank having been previously grooved and roughed out in any usual or preferred manner.

The gear-- the rollers 200 and dle is stopped and also the is engaged at,

rotated thrdugh one blank at the right-hand end thereof. Then the machine is started, the sleeve 79 and-the operating shaft 13loperating alternately insuccession. During the rotati've movement of the blank, relieving movements of the tool are effected as described, thus cutting the desired relief. on the teethof the blank. After one complete revolution of the blank the rotative movement of the spin relieving movements of the tool. The carriage is then fed longitudinally toward theleft, the blank turning slightly in conformity with' the helical teeth. Just prior to the longitudinal movement the tool slide, the former pin and tool. are moved rearward,

thus withdrawing the former pin from they former and moving the tool into a groove in the blanle After the longitudinal move- .ment the tool slide is moved forward, thus returning the former pin to the former which a new position. The tool assumes a corresponding position with respect to theblank. After this movement of the tool and former pin the blank is again revolution and these movements are repeated alternately in succession until the blank is completely formed. It will be seen that with the step-by-step movements described and with 'a fine' feed the former pin can follow or climba'very sharply inclined portion of the contour of the former, the tool being caused to cut a similarly inclined part of the contour of the.

cutter. 4 g c What I claim is:

1. The herein described method consisting in axially rotating a blank, in providing acutting tool in position to engage the blank at the front thereofand cut it, in providing a former having a contour the reverse of that with which the blank is to be shaped, in providing a former pin connected with the tool and normally engaging the former at the rear thereof, and in effecting relative feeding movement former and between the tool and the work longitudinally of the latter, the former pin following the contour of the former and thus causing the tool to cut the said contoiir on the blank. i

2. The herein described method -consisting in axially rotating a blank, in providing a cutting tool in position to engage the blank at the front thereof and cut it, in providing'a former having a contour the reverse of that with which theblank is to be shaped, in providing a former pin connected with the tool and normally engaging th eformer at with the betweenthe pin and the termittent feeding weenie the reai thereof, and in efiecting relative intermittent feeding movements between the pin and the former former pin ll'owing the contour of the former and thus causing the tool to cut the said contour on the blank.

3. The herein described method consistingin axially rotating a blank, in providing a cutting tool in position to engage the blank at the front thereof and cut it, in providing a former having a contour the reverse of that with which the blank is to be sha ed, in providing with the tool and normally engaging the former at the rear thereof, in effecting relative intermittent feeding movements between the pin and the former and between the tool and the work longitudinally of the latter, the former pin following the contour of theformer and thus causing the tool to cut the said contour on the blank, and in separatin and between the tool and the work lorigitudinally of the latter, the

a former pin connected the pin and the former at the time of each I ing in axially rotating a'zblank, in provid-. en'gagethe ing a cutting tool in position to blank at the front thereof and cut it, in providing a former having a contour the reverse of that with which the blankis tobe shaped, in providing a former pin connected tool and normally engaging the former at the rear thereof, in effecting, relative intermittent feeding movements between the pin and the former and between the tool and the'work longitudinally of the latter, the former-pin following the contour of the former and thus causing the tool to cut the said contour on the blank, and in withdrawing the pin rearward from this former'at thejtime of each feeding movement and returning the pin toengagement with the former after each longitudinal movement. I

5. The herein described method consisting in axially rotating a blank having generally longitudinal grooves therein, in providing a cutting tool in position to engage the blank at the front thereof and out it, in providing a former having a contour the reverse of that with which the blank is; to .be shaped,

in providing a former pin connected with the tool and normally engaging the former at the rear thereof, in effecting relative inmovements between the pin and the former and. between the tool and the work longitudinally of the latter and intimed relatlon to the blank rotation so that each movement takes place with the tool opposite a groove, the former pin following the contour'of the former and thus causing the tool to cut the said contour on the b lank, and in withdrawing the pin rearnaeaeae ward from the former and moving the tool rearward into the groove at the time of each longitudinal movement and returning the pin to engagement with the i'ormer and correspondingly returning the tool after each such movement.

6. The herein described method consisting in axially rotating a blank having generally pin and longitudinal grooves therein, in providing a cutting tool in position to engage the blank at the front thereof and cut it, in providing a former having a contour the reverseof that with which the blank is to be shaped,

in providing a former pin connected with the tool and normally engaging the former at the rear thereof, in efi'ecting relative in-- termittent feeding movements between the the former and between the tool and the work longitudinallyof the latter and in timed relation to the blank-rotation so that eanh movement takes place with the tool opposite a groove, the former pin following the contour of the former and thus .causing the-tool to cut the said contour on the blank,

in stopping the blank rotation at the time of each longitudinal movement, and in withdrawing the pin rearward from the former and moving the tool rearward into the-groove at the time of each longitudinal movement and returningthe pin to engagement with the former and correspondingly returning the tool after each such move ment.

.7. The herein described method consisting in axially rotating a blank having generally longitudinal helical grooves therein, in pro vidlng a cutting tool in position to engage the blank at the front thereof and cut it, in

providing a former having a contour the reverse of that with which the blank is to be shaped, in providing a former pln connected with the tool and normally engaging theformer at the rear thereof, in effecting relative intermittent feeding movements between the pin and the former and between the tool and the work longitudinally of the latter and in timed relation to the blank rotation so that each of the several successive movements takes place with the tool opposite one of the helical grooves, the ,former pin following the contour of the former and thus causing the tool to cut the said contour on the blank, and in withdrawing the pin rearward from the former and moeving'the tool rearward into the groove at the time of each reverse of that to which the blank is to be shaped, in providing a former pin connected with the tool and normally engaging the former, in 'efiecting relative intermittent feeding movements between the blank and the tool, in moving the tool toward and the former pin away from the former member prior to each feeding movement, and in returning the former pin into engagement with the former member after each feeding movement. v

In testimony whereof, I hereto aflix my signature.

, FRIEDERICH MULLER. 

